Furnace wall anchoring structures



Jan. 3, 1967 K. .1. KETTNER 3,295,280

FURNACE WALL ANCHORING STRUCTURES Filed April 9, 1964 f gt! 84 2 INVENTOR. 74 3 BY 2 M 76 f l y & 71H; ,5.

existent in most high temperature furnaces. 'construction or fabrication of the refractory lined furponents of the wall.

United States Patent 3,295,280 FURNACE WALL ANCHQRING STRUQTURES Kay I. Kettner, Western Springs, Ill., assignor to The S. Obermayer (10., Chicago, llll., a corporation of @hio Filed Apr. 9, 1964, Ser. No. 358,511 9 Claims. Cl. 52--378) This invention relates to improved anchoring structures finding utility as supporting or retaining means for refractory walls or linings in metallurgical furnaces. More particularly, the invention is directed to a springloaded or spring-tensioned anchoring structure useful as retention means for holding monolithic plastic refractory walls in close contact with a steel retaining shell or lattice. In a specific preferred embodiment the invention is directed to anchoring devices for supporting and tensioning refractory walls in rectangular soaking pit furnaces.

Also included within the scope of this invention are methods for constructing the improved walls of the refractory furnaces. The composite wall structure produced in accordance with the practice of the invention have been found to exhibit extraordinary stability and to have greatly improved properties.

In the prior art fabrication of metallurgical furnaces, it has been the practice to anchor the refractory wall to 'the enclosing steel shell or skeleton by means of a boltlike metallic accessory which is keyed in the refractory material, extends through a hole in the steel shell, and is secured with a standard nut and washer or any equivalent means. The principal purpose of the bolt-like accessory or attachment is to keep the refractory wall in close contact with the steel supporting structure at all times.

The support and retention of refractory walls or refractory linings of the type in which the present invention finds utility poses special problems not generally During the nace, thermal expansion stresses develop due to the difference in the thermal expansion coefficients of the com- As a result there is a tendency for the refractory wall to separate from the steel supporting structure. This separation is often the beginning of ultimate wall failure. While the prior art bolts and boltlike accessories have provided support and bonds for the refractory lining, the rigidity and inexpansibility of such supports have caused fractures in the walls, breaking of the retaining refractory anchor and concurrent wall failures. The problems posed by shock, vibration, permanent elongation of the supporting bolt, and temporary expansions and contractions of the bolt and of the metallic shell in response to temperature variations have not been solved by the prior art structures and no such structures have proved completely satisfactory for the purpose intended. It is the aim of the present invention to provide a simple and highly satisfactory solution to the prior art shortcomings and to eliminate the prior art problems through the use of an improved refractory wall anchoring assembly.

It is a principal object of the invention to provide a refractory anchor or anchor assembly which includes tensioning means to reduce the possibility of fracture of the refractory anchor.

It is a related object of the invention to provide a refractory wall anchor assembly which holds the wall and its supporting structure in positive tension at all times.

Another object of the invention is to provide a refractory wall anchor assembly which includes a tension relieving bolt and permits limited movement of the refractory wall with respect to the supporting steel structure.

Still another object of the invention is to provide a refractory wall anchor which will withstand the stresses of shock and vibration and which will automatically compensate for permanent or temporary changes in the length of the anchoring mechanism and which will accommodate temporary expansion and contraction of the wall components in response to temperature variations.

Another object of the invention is to provide a wall anchoring device which will relieve the tension of monolithic plastic refractory wall construction in rectangular soaking pit furnaces.

Additional objects and aims of the invention include the following:

To provide a refractory wall anchor means which is simple in construction and which is readily incorporated into the furnace as a physical element thereof; to provide an anchor, support, and retention means for a refractory wall, which anchor will obviate the causes of premature failures in soaking pit wall construction; to provide a refractory wall anchor which will undergo compensating elongation in the event of slumping, settling, or weight compression of plastic refractory; to provide a refractory anchor which will be responsive to the relative movements between the steel enclosure and the refractory wall lining without causing either fracture of the refractory wall or failure of the anchor; and to provide a refractory wall anchor assembly which can be installed in existing furnaces and in new furnaces.

Other and further objects and advantages of the invention will become apparent from a reading of the following specification taken in conjunction with the drawing in which:

FIGURE 1 is a cross-sectional view of a single coil spring embodiment of an anchor assembly embodying the principles of the invention;

FIGURE 2 is a cross-sectional view of another singlesp-ring anchor mechanism embodying the principles of the invention;

FIGURE 3 is a cross-sectional view of still another embodiment of the invention utilizing a single-spring anchor assembly;

FIGURE 4 is a sectional view taken along the line 4-4 of FIGURE 3;

FIGURE 5 is a cross-sectional view of another embodiment of a single-spring anchor assembly;

FIGURE 6 is a sectional view taken along the line 66 of FIGURE 5;

FIGURE 7 is a cross-sectional view of a double coil spring anchor assembly embodying the principles of the invention;

FIGURE 8 is a cross-sectional view of a double band spring anchor assembly embodying the principles of the invention; and

FIGURE 9 is a cross-sectional view of an anchor assembly similar to that depicted in FIGURE 8 but illustrating an alternative method of attachment to the sup porting shell.

The tensioning anchoring assemblies of the present invention find utility in furnaces having monolithic plastic refractory walls and are useful particularly in the construction of rectangular soaking pit furnaces. In furnaces of this type, premature failures maybe due to one or more of the following causes: Slumping, settling, or weight compression of the plastic refractory in its green state, movement of steel enclosures due to expansion, contraction, mechanical abuse, excessive heat conductivity, and partial enclosure failure.

The use of plastic refractory materials in the fabrication of furnaces is described in Patent No. 2,949,704. Additional information pertaining to the gunning or ramming operations used in the fabrication of the plastic 3 monolithic wall structures is found in application Serial No. 228,003 filed October 3, 1962, now US. Patent No. 3,197,315, issued July 27, 1965. The general techniques involved are now well-known in the art and no detailed discussion is required herein. For the purpose of general background and reference and additionally for the purpose of providing an environmental setting for the anchoring device of the invention, certain basic steps in the fabrication of a monolithic plastic wall furnace will be referred to briefly. For example, in the fabrication of a rectangular soaking pit furnace, the refractory composition, which is an aggregate, is applied to the retaining steel walls of the furnace and rammed or gunned into place. The composition is of a nature such that it is susceptible to agglomeration in its preferred or green state and the agglomeration has a certain degree of rigidity and firmness so that the material is self-supporting even prior to the firing step.

Considering now the fabrication of a single wall of the furnace, the plastic material is applied to the lower portion of the wall to a finite limited height of, for example, about two feet. A course of super duty refractory anchor tile which serves as anchors is now placed in position at spaced intervals along the wall. The positioning of these anchors corresponds with cooperating holes extending through the steel shell of the furnace and the anchor is connected to the steel shell by means of the anchor device of the invention.

Additional plastic material is rammed into position above the course of spaced anchors to embed the anchors in the wall and when the wall height has been built up to a predetermined higher level, another course of spaced anchor bricks or anchor tiles is placed in position and fastened through the steel wall. This process is continued until the wall has been built to the desired height. The anchors retain the plastic refractor material in contact with the steel enclosure. Finally, the entire composite structure is fired to provide a one-piece or monolithic refractory wall.

Referring more particularly to the drawing, there is shown in FIGURE 1, for the purpose of illustrative disclosure, a preferred embodiment of one form of the anchor assembly of the invention. In the embodiment of the invention illustrated, there is shown a section of a furnace wall 11 consisting of an outer metallic shell 13 and an inner core, refractory wall, or lining 15. Extending laterally through a hole 17 in the steel shell 13 is an anchor bolt or tie 19 which consists of an elongated stud or rod 21 having a generally fiat transverse head 23. A load plate 24 adjacent the head 23 is anchored within the refractory wall or the lining 15 of the furnace. At its other end 25 the stud is threaded 27 and extends through and exteriorly of the metallic shell 13. The head and the cooperating load plate 24 of the anchor bolt are keyed to and the plate bears against an anchor tile or block 29 embedded in the plastic refractory wall material 15. The threaded end 25 of the anchor bolt 19 is secured to the steel shell 13 and a compression spring 31 is retained in position between the end of the bolt 19 and the shell 13 by means of a nut 33 and washers 35. A lock-nut 37 precludes the loosening of the nut 33 which serves to adjust or to regulate the tension of the spring 31. Spot welding or other techniques may be used to prevent loosening of the nuts on their supporting threaded stud.

The springs utilized in the practice of the invention are selected to have precise tensioning properties. The particular installation will, of course, determine the exact specifications of the springs used. In general, however, springs in the range of about 100 pounds to about 500 pounds per inch are preferred, these values being consistent with the mechanical strength of the refractory anchors used in the monolithic wall.

With this arrangement it will be apparent that regardless of the temperature variation in the furnace and in the furnace wall structure, the monolithic wall will be held resiliently urged toward its bounding shell. Lateral separation of the refractory wall from the metallic shell is effectively prevented. The retaining anchors or ties 19 will hold the monolithic wall in place while permitting a limited degree of freedom of expansion and contraction of the relative parts with respect to each other.

The resilient tensioning and anchor mechanism illustrated in FIGURE 2 is substantially the same as that shown in FIGURE 1 except that a leaf-spring 40 is used rather than the coil spring 31 of FIGURE 1. The leafspring 40 is locked in position on the threaded end 25 of the anchor bolt 19 by means of a pair of nuts 42 and 44. The arms 46 of the leaf-spring 4t bear against the outer surface of the metallic shell 13 of the furnace wall structure.

In a somewhat modified form of the invention, as illustrated in FIGURES 3 and 5, the spring of the resilient anchor mechanism bear against a channel section or channel member 50 displaced somewhat inwardly of the external shell 13 of the furnace but connected thereto.

The anchor assemblies of FIGURES 1 through 6 depict structures utilizing a single spring in each case. In another preferred embodiment of the invention, double tension springs are used to provide duo-directional or bilateral tensioning. The use of coil springs in such an embodiment is illustrated in FIGURE 7, and FIGURES 8 and 9 illustrate the use of leaf or band springs. Referring now to FIGURE 7 the anchor bolt of the invention is depicted as consisting of an elongated stud 52 having a head portion or bearing plate keyed against an anchor tile embedded in the refractory wall of the furnace as described with reference to FIGURE 1. The stud 52 extends through a channel 58 and through the steel shell 13, and a pair of coil springs 60 and 62 encircle the shaft of the stud, one spring being positioned and retained within the channel internally of the wall 13 and the other spring being retained externally of the wall 13. Tensioning and retention of the springs in position is insured by means of washers 35 and nuts 64, 66 and 68.

It will be readily apparent that in the preferred embodiment depicted in FIGURE 7 lateral movement of the refractory Wall in either direction with respect to the steel shell is controlled and, in effect, the monolithic refractory wall is resiliently mounted with respect to the engulfing or enclosing steel shell.

In FIGURES 8 and 9 the resilient anchor assembly of the invention is depicted as including a pair of opposing leaf or band springs 70 and 72 which, in the case of FIGURE 8, are fastened to the anchor bolt 74 within a channel 76 internally of the exterior wall or shell 13 by means of lock nuts 86 and 82. In FIGURE 9 leaf springs 70 and 72 are retained in a channel 84 which is external of the shell 13. Locking nuts 89 and 82 threaded on to the end of the anchor bolt hold the leaf spring in fixed position. The operation of the spring structure of FIGURES 8 and 9 is the same as that previously described with respect to FIGURE 7.

In accordance with the practice of the invention, it has been found that maintaining the refractory wall anchoring mechanism in positive tension at all times reduces the tendency for the refractory wall to separate from the retaining steel structure. The provision of a resilient support system rather than a rigid system has the important result of minimizing mechanical fissure of the wall and eliminating fracture and failure of the retaining anchor. The adverse effects of both mechanical and thermal shock are minimized and greatly extended life of the overall structure is achieved.

While disclosures of preferred embodiments of the apparatus and of preferred methods for assembly and installation of the apparatus of the invention have been provided, it will be apparent that numerous modifications and variations thereof may be made without departing from underlying principles of the invention. It is, there-- fore, desired by the following claims to include within the scope of the invention all such variations and modifications by which substantially the results of this invention may be obtained through the use of substantially the same or equivalent means.

What is claimed is:

1. In a furnace of the soaking pit type, and including a monolithic plastic refractory wall and a metallic shell retaining said wall, the improvement comprising resilient anchor means connecting said wall with said shell for maintaining said wall and said shell coupled in stressed and yieldable relation, said resilient anchor means including an anchor member and a cooperating spring means resiliently urging said wall and said shell toward each other.

2. In a soaking 'pit furnace having a metallic outer shell and a monolithic plastic refractory wall contiguous to and substantially coextensive with said shell and disposed therewithin, the improvement comprising a plurality of horizontally disposed wall anchoring assemblies connecting said wall to said shell, each said anchoring assemblies including an anchor member and cooperating spring means and constituting resiliently yieldable tensioning means intercoupling said wall and said shell and biasing said wall toward said shell resiliently to oppose movement of said wall inwardly of said shell.

3. In a soaking pit furnace having a metallic outer shell and a monolithic plastic refractory wall contiguous to and substantially coextensive with said shell and disposed therewithin, the improvement comprising horizontally disposed anchors connecting said wall to said shell, each said anchors including a pair of opposed resiliently yieldable spring means comprising tensioning members interconnecting said wall and said shell and biased resiliently to oppose lateral movement of said wall with respect to said shell.

4. In a soaking pit furnace having a metallic outer shell and a monolithic plastic refractory wall contiguous to and substantially coextensive with said shell and disposed therewithin, the improvement including:

a plurality of spaced resilient wall anchors urging said refractory wall and said shell toward one another for stress responsive resilient contact therebetween,

each said anchors comprising an elongated bolt, said bolt being generally T-shaped and having a head portion and a stud portion,

said stud portion extending into an opening extending laterally into said refractory wall and through an aligned hole in said shell,

said head portion of said bolt being keyed with said refractory wall to preclude radially outward displacement of said bolt with respect to said wall,

spring means resiliently coupling said bolt to said shell and disposed to resist displacement of said refractory wall radially inwardly of said shell;

whereby said anchor is effective to couple said wall and said shell through tensioning and resilient forces.

5. In a high temperature metallurgical furnace having a metallic shell and a refractory lining or wall contiguous with and substantially coextensive with said shell and disposed therewithin, the improvement including:

a bolt'like wall anchor maintaining said refractory wall resiliently urged radially toward said metallic shell,

said anchor comprising an elongated stud extending into an opening in said refractory Wall and into an aligned cooperating hole in said metallic shell,

load plate means connected to one end of said stud and seated against an internal surface of said wall to preclude withdrawal of said stud radially outwardly of said wall, said stud being held fixed with respect to said wall against separation therefrom in response to radial forces impressed upon said stud,

spring means adjacent a threaded end of said stud and spring retention means stressing against said shell and urging said stud radially outwardly of said metallic shell; whereby said stud is urged radially outwardly to maintain said wall keyed in resilient stressed contact with said metallic shell while permitting freedom of expansion and contnaction of component elements of said furnace under the influence of temperature changes in said furnace. 6. In a high temperature metallurgical furnace having a metallic shell and a refractory lining or wall contiguous with and substantially coextensive with said shell and disposed therewithin, the improvement including:

a bolt-like wall anchor maintaining said refractory wall resiliently urged toward said metallic: shell, said anchor comprising an elongated stud extending into an opening in said refractory wall and through an aligned cooperating hole in said metallic shell, load plate means connected to one end of said stud and seated against an internal surface of said wall to preclude withdrawal of said stud outwardly of said wall, said stud being held fixed with respect to said wall against separation therefrom in response to radial forces impressed upon said stud, first spring means adjacent a threaded end of said stud and positioned laterally outwardly of said shell to urge said stud laterally outwardly of said shell, second spring means positioned laterally inwardly of said first spring means and inwardly of said shell to urge said stud laterally inwardly of said shell, and spring retention means on said stud to preclude dislodgment of said first and said second spring means axially of said stud in directions away from said metallic shell therebetween; whereby said anchor is retained in resilient and tensioned disposition with respect to said shell and whereby said anchor permits limited tensioned bilateral movcment of said refractory wall with respect to said shell. 7. In a high temperature metallurgical furnace having a metallic shell and a refractory lining or wall contiguous with and substantially coextensive with said shell and disposed therewithin, the improvement including:

a bolt-like wall anchor maintaining said refractory wall resiliently urged toward said metallic shell, said anchor comprising an elongated stud extending into an opening in said refractory wall and through an aligned cooperating hole in said metallic shell, load plate means connected to one end of said stud and seated against an internal surface of said wall to preclude withdrawal of said stud outwardly of said wall, said stud being held fixed with respect to said wall against separation therefrom in response to radial forces impressed upon said stud, first spring means adjacent a threaded end of said stud and positioned laterally outwardly of said shell to urge said stud laterally outwardly of said shell, second spring means positioned laterally inwardly of said first spring means to urge said stud laterally inwardly of said shell, and spring retention means on said stud to preclude dislodgment of said first and said second spring means axially of said stud; whereby said anchor is retained in resilient and tensioned disposition with respect to said shell and whereby said anchor permits limited tensioned bilateral movement of said refractory Wall with respect to said shell. 8. In a high temperature metallurgical furnace having a metallic shell and a refractory lining or wall contiguous with and substantially coextensive with said shell and disposed therewithin, the improvement including:

a bolt-like wall anchor maintaining said refractory wall resiliently urged toward said metallic shell,

said anchor comprising an elongated stud extending into an opening in said refractory wall to engage said wall and adapted to fasten to said shell,

load plate means connected to one end of said stud and seated against an internal surface of said wall to preclude withdrawal of said stud outwardly of said wall, said stud being held fixed with respect to said wall against separation therefrom in response to radial forces impressed upon said stud,

auxiliary wall means displaced laterally of said shell and extending substantially parallel with respect thereto,

Wall support means to hold said auxiliary wall means fixed with respect to said shell and spaced therefrom,

said wall means and said shell defining a channel there between into which said stud extends,

spring retention means within said channel and connected to said stud to preclude displacement of said spring means axially along said stud, said spring means adapted to urge resiliently against opposed facing surfaces of said shell and said wall means defining said channel;

whereby said anchor is retained in resilient and tensioned disposition for movement laterally inwardly and outwardly to provide limited bilateral tensioned movement of said refractory wall with respect to said shell.

9. In a furnace, the combination with a monolithic plastic refractory wall and a shell retaining said wall, of anchor means interconnecting said wall and said shell and tensioning said wall with respect to said shell, said anchor means including an anchor bolt coupling said wall to said shell and cooperating spring means resiliently biasing said wall toward engagement with said shell thereby maintaining said anchor bolt under tension to clamp said wall resiliently against said shell.

References Cited by the Examiner UNITED STATES PATENTS 1,617,555 2/1927 Vallentin 52-573 X 1,736,704 11/1929 Gilbert 52379 X 1,783,383 12/1930 Montrief 52573 X 1,807,868 6/1931 Nygaard 52573 X 1,910,160 5/1933 Gorman 52573 X 1,928,313 9/1933 Gaylord 52378 1,941,492 1/1934 Royall 52378 2,011,312 8/1935 Engman 52--223 2,689,987 9/1954 Berger 52-573 X 2,854,842 10/1958 Hosbein et al. 1101 X 3,203,376 8/1965 Engelhardt 1l0l FRANK L. ABBOTT, Primary Examiner.

RICHARD W. COOKE, JR., Examiner.

M. O. WARNECKE, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 295 280 January 3 1967 Kay J. Kettner It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 36, "refractor" should read refractory Column 5, line 10, "for" should read and Signed and sealed this 5th day of August 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

1. IN A FURNACE OF THE SOAKING PIT TYPE, AND INCLUDING A MONOLITHIC PLASTIC REFRACTORY WALL AND A METALLIC SHELL RETAINING SAID WALL, THE IMPROVEMENT COMPRISING RESILIENT ANCHOR MEANS CONNECTING SAID WALL WITH SAID SHELL FOR MAINTAINING SAID WALL AND SAID SHELL COUPLED IN STRESSED AND YIELDABLE RELATION, SAID RESILIENT ANCHOR MEANS INCLUDING AN ANCHOR MEMBER AND A COOPERATING SPRING MEANS RESILIENTLY URGING SAID WALL AND SAID SHELL TOWARD EACH OTHER. 